Hundreds of people leaving a late-night rap concert on a beach in Guinea rushed to leave through a single exit, creating a stampede that killed at least 33 people, officials said Wednesday.

The victims included children as young as 10, and most bodies brought to an overflowing morgue in the capital were still dressed in bathing suits and swim trunks. Some had bled from their mouths after their small bodies were trampled, causing internal bleeding.

“We are not used to seeing such a large number of bodies at the same time. It’s such a tragedy, these young victims killed in the prime of their life,” said an employee at Donka Hospital where bodies awaited burial.

The hospital’s director, Dr. Fatou Sike Camara, announced the toll of 33 deaths.

President Alpha Conde went on national television to declare a week of national mourning and promised a full investigation. The capital’s beaches also were ordered closed until further notice.

“The president calls on authorities at all levels to take the necessary steps so that this same tragedy never happens again in our country,” his office later said in a statement.

More than 700 people had gathered on the beach in Conakry, the capital city, for a concert celebrating the end of the holy Muslim month of Ramadan, which featured the Guinean rap groups Instinct Killers and Banlieuzart.

Witnesses said the stampede happened after the show ended as the large crowd tried to exit through a small gate. Some people fell to the ground and were trampled.